This invention relates to a new and improved, compact rotary variable differential transformer having an eccentric rotor core.
Rotary variable differential transformers (RVDT) are well known transducer devices used for measuring angular displacement. Mechanical angular displacement or rotation is converted into an analog electrical signal suitable for processing, control, display, etc. RVDT's typically include a primary winding, a pair of secondary windings, a rotor and a stator. An input voltage is supplied to the primary winding which induces an output voltage across the secondary windings, the magnitude of which is dependent upon the angular displacement and position of the rotor. This position determines the magnetic coupling between the primary and secondary windings which in turn determines the magnitude of the output voltage. The rotor, of course, is coupled to the element whose angular displacement is to be determined. Exemplary RVDT's are shown in U.S. Pat. Nos. 4,347,491, 4,551,699, 3,882,436 and 3,818,401, and in Herseg, Edward E., "Handbook of Measurement and Control", Schaefitz Engineering, Pennsanken, N.J.
A principal problem with these and other prior art RVDT's is that the linear operating ranges of the RVDT's are very narrow. The reason for this is that the voltage output curves are symmetrical which tends to narrow the linear region of the curves between the positive nd negative peaks. Another disadvantage of many prior art devices is the complicated, oftentimes bulky structure of the devices.